I think that the Army and Air Force cultures are almost polar opposites, to the extent that joint training will not work for Army units.

For example, the Air Force is a time driven organization, and the Army is a mission driven organization. The ATO cycle drives the Air Force, to the extent that, except for planned flexibility, they can't or won't flex it, in my experience.

Another example is training CAS requests. The Air Force wants to program training CAS a year out. That means that if I drop a request the day I return from deployment, I might get supported the last 30 days before I deploy again (when I have essentially stopped training to ship my stuff and gives guys a break with their families). I can't lock in training resources until 8 weeks or so, so I train with Navy or USMC CAS.